Mouthparts

honey bee mouthparts

Mouthparts of honey bee worker (posterior view). After Michener (1974, fig. 1.6) [1]. The mouthparts are unfolded and spread apart. Most of the time they are folded behind the head and held together. See also mechanism of folding of the mouthparts.

Cd - cardo (plural cardines)
Ga - galea
Gls - glossa (tongue)
Lbl - labellum
LbPlp - labial palpus
Lr - lorum [2], submentum [1]
MxPlp - maxillary palpus
Pgl - paraglossa
Pmt - postmentum [2], mentum [1]
Prmt - prementum
St - stipes


The glossa is similar to a long cylinder. The diameter of the glossa is 185.0±1.5 micrometers at the base and 96.6±0.3 micrometers in the middle part. The glossa consists of segments. Length of one segment is about 23 micrometers. On apical part of each of the segments there are 16-20 hairs. The hairs on basal part of the glossa are stiff and short (32 - 63 micrometers long), whereas the hairs on the middle and apical part are longer (171.9±0.3 micrometers long) [3]. At the apex of the glossa there is a spoon-like flabellum. The mouthparts are cleaned with foreleg tarsi [4].

Ingesting liquid food by bees is based on mechanism of "viscous dipping" [5]. The tongue is extended and immersed into nectar. At this stage hairs on the glossa erect asynchronously [6][7] and trap the nectar [8], see also video [5]. The erectable hairs can increase the ability of a bee to collect nectar [3]. Next, when coated with nectar, the glossa is retracted to a tube formed from galeae and labial palpi. Then the nectar is sucked into pharynx. There are ridges on the inner wall of galeae which can reduce friction during drinking [9][10]. Honey bees are able to imbibe 1.8 microlitres of diluted nectar per second [11]. This rate is lower in case of higher concentrations of nectar [11]. It was suggested that the optimal for bees concentration of sugar in nectar, which is a compromise between energy content and intake speed is about 52% [5] but see [3]. There are sensory organs on the mouthparts which facilitate the food intake [12][13][14][15].

References

  1. Michener C.D. (1974) The social behavior of the bees: a comparative study. Harvard Univ. Press., Cambridge, Mass.
  2. Snodgrass R.E. (1956) Anatomy of the honey bee. Comstock Publishing Associates, Ithaca, pp. 334.
  3. Yang H., Wu J., Yan S. (2014) Effects of erectable glossal hairs on a honeybee's nectar-drinking strategy. Applied Physics Letters 104:263701.
  4. Linghu Z., Wu J., Wang C., Yan S. (2015) Mouthpart grooming behavior in honeybees: kinematics and sectionalized friction between foreleg tarsi and proboscises. Journal of insect physiology.
  5. Kim W., Gilet T., Bush J.W.M. (2011) Optimal concentrations in nectar feeding. Proc. Natl Acad. Sci. USA 108:16618-16621.
  6. Wu J., Zhu R., Yan S., Yang Y. (2015) Erection pattern and section-wise wettability of a honeybee's glossal hairs in nectar feeding. Journal of experimental biology (in press).
  7. Zhao J., Wu J., Yan S. (2015) Erection mechanism of glossal hairs during honeybee feeding. Journal of Theoretical Biology 386:62–68.
  8. Simpson J., Riedel I. (1964) Discharge and manipulation of labial gland secretion by workers of Apis mellifera (L.)(Hymenoptera: Apidae). Proceedings of the Royal Entomological Society of London 39:76–82.
  9. Li C., Wu J., Yang Y., Zhu R., Yan S. (2015) Drag Reduction in the Mouthpart of a Honeybee Facilitated by Galea Ridges for Nectar-Dipping Strategy. Journal of Bionic Engineering 12:70–78.
  10. Li C.-C., Wu J.-N., Yang Y.-Q., Zhu R.-G., Yan S.-Z. (2016) Drag reduction effects facilitated by microridges inside the mouthparts of honeybee workers and drones. Journal of theoretical biology 389:1–10.
  11. Roubik D.W., Buchmann S.L. (1984) Nectar selection by melipona and Apis mellifera (Hymenoptera: Apidae) and the ecology of nectar intake by bee colonies in a tropical forest. Oecologia 61:1-10.
  12. Galić M. (1971) Die sinnesorgane an der glossa, dem epipharynx und dem hypopharynx der arbeiterin von Apis mellifica L. (Insecta, Hymenoptera). Zeitschrift für Morphologie der Tiere 70:201–228.
  13. Whitehead A.T., Larsen J.R. (1976) Electrophysiological responses of galeal contact chemoreceptors of Apis mellifera to selected sugars and electrolytes. Journal of insect physiology 22:1609–1616.
  14. Masuko K. (1986) Motor innervation and proprioceptors of the mouthparts in the worker honey bee, Apis mellifera. I. Mandibular nerve. Journal of Morphology 188:51–67.
  15. Masuko K. (1989) Motor innervation and proprioceptors of the mouthparts in the worker honey bee Apis mellifera. II. Maxillary and labial nerves. Journal of Morphology 201:23–37.